1. Field of the Invention
The field of this invention is the mining industry, particularly the bulk blending of natural resources such as coal to meet parameter requirements such as, among others, percentage of sulfur content.
2. Brief Description of the Prior Art
The field of application concerns many mining resources, but without loss of generality and to promote the understanding of the invention through a specific example, the coal mining industry shall be considered.
It is becoming increasingly difficult for a single seam of coal to be directly mined, shipped, and burned. As restrictions increase, efforts must be made to clean, treat, or modify the coal to meet certain parameter requirements. In the coal business, it is necessary to produce batches of coal that have particular percentages of, among others, sulfur, ash, moisture, and Btu/lb characteristics. These requirements are set and must be implemented by coal miners, coal preparation (wash) plants, coal brokers, and large users of coal such as utilities, factories, and others.
One method of obtaining a useable coal is to mix several coals together to form a blend. If appropriately mixed, the resulting blend may meet the requirements even if each separate coal does not.
However, it is difficult to determine the blend ratios that simultaneously satisfy all the requirements. The manual method used by most companies involves sampling the coals and making a guess at how to blend it. After sampling the resulting blend, another guess is made and so on.
Advances in this manual process were made in 1982 by Jasper Communications, of Jasper, Indiana. Jasper Communications made and sold a computer program called Perfect Blend. Perfect Blend was designed to find the minimum cost blend out of up to 250 stockpiles of coal. Perfect Blend considered 10 parameters for each coal type and the minimum and maximum requirement limit for each parameter. In finding the minimum cost blend it considered only the blends which simultaneously satisfy the parameter limits.
Further advances were made in The Coal Blending Solution program developed independently in 1987 by the present inventor. The Coal Blending Solution (hereinafter referred to as CBS) enables the user to minimize any parameter chosen. For example, the ability to maximize Btu/lb is important to those miners who are paid a premium for high Btu/lb coal. Others may wish to maximize percent sulfur in order to use their high sulfur coal, yet not exceed the required limit in the final shipment. And still others may wish to find a minimum cost blend in order to make a bid proposal that will meet parameter limits. The CBS does not limit the number of parameters or the choice of the parameters considered. It also provides a means of forcing part or all of a stockpile to be used.
The CBS also provides a means of determining the stability of an optimal blend. A blend is stable, if small changes in the blend ratios result in a blend that is still feasible (i.e. a blend that meets all the parameter requirements). Because of the inaccuracies in the actual mixing processes and the approximate nature of the parameter data used in determining a blend, it is important to determine a blend that is stable.
The CBS identifies the stability of an optical blend. If it is insufficiently stable, the CBS provides a means of allowing the user to reoptimize to obtain a more stable result. And if no blend is possible within the parameter limits, the CBS determines this and can aid the user in identifying alternatives.
CBS and Perfect Blend can only determine a blend for one period such as one day for the requirements of only one batch of coal such as the batch for one power utility at a time. CBS and Perfect Blend cannot differentiate and optimize the blending for more than one batch for more than one power utility considered simultaneously. Consequently, the user cannot optimize its profits due to increased revenue over costs from several utilities. CBS and Perfect Blend can not distinguish between a blend that can be used raw and a blend sent to one or more preparation plants prior to blending. Furthermore, if multiple days and/or multiple batches for more than one power utility are simultaneously considered, memory limitations and increased processing time prevents or hinders a practical solution. Of course, no stability features are present for the multiple period (e.g. 31 days), multiple utility, and multiple preparation plant case since none of these features are themselves considered by either CBS or Perfect Blend. A need therefore arose for a system for optimal usage of multiple day and utility blending while minimizing the processing time and computer memory storage needed to practical levels.